public class L70 {

    public static void main(String[] args) {

        int stairs = new Solution().climbStairs(3);
        System.out.println(stairs);

    }


    static class Solution {
        public int climbStairs(int n) {
            if (n <= 2) {
                return n;
            }

            int[] dp = new int[n + 1];

            dp[0] = 0;
            dp[1] = 1;
            dp[2] = 2;

            for (int i = 3; i <= n; i++) {
                dp[i] = dp[i - 1] + dp[i - 2];
            }

            return dp[n];

        }
    }
}
